Constructing worlds

Question 1

What does retinotopic reffer to?

Answer 1

That visual organisation relates to where things are occuring in visual space. Light falling on a particular part of our retina.

Question 2

What is largely responsible for conscious visual experience?

Answer 2

The retinogeniculate pathway.

Question 3

What is the difference between the retinogeniculate pathway and the LGN?

Answer 3

Retinogeniculate pathway: a pathway responsible for transmitting visual signals from the eyes to the primary visual cortex (inclues LGN).

Lateral Geniculate Nucleus: specific structure within the thalamus. serves as a relay station for visual information traveling from the retina to the primary visual cortex. Organized into six layers,

Question 4

What does the binocular visual feild allow for?

Answer 4

Locate objects in depeth.

Question 5

How could you describe our visual processing arragement?

Answer 5

As contralateral. Opposite side processing.

Question 6

What would occur with a unilateral lesion (left) of the primary visual cortex?

Answer 6

Loss of concious visual experience pertaining to the right side of visual information.

Question 7

What is the difference between Retinotopic and Tonotopic organisation?

Answer 7

Retino: refers to vision, where things objects are in the world matters
Tono: refers to hearing, frequency and amplitude matters

Question 8

What does cortical cell density in the in the primary visual cortex relate to?

Answer 8

More cells are devoted to the fovea than periphery.
More ganglion cells from fovea needs more cells to process.

Question 9

What do cortical collumns in the PVC represent?

Answer 9

Each processes a small region of space. When tiled together that represent the entire visual feild. Orientation sensitivity emerges.

Question 10

Broadly explain the receptive feild of LGN cell.

Answer 10

Light falls on a region of the retina which has a cluster of photoneuron receptors. These are arranged so that that particular pattern of light might have an inhibitory or excitatory affect. Position of object/light pattern matters.

Question 11

What is the function of simple cells?

Answer 11

Simple cells are essentially configurations of photo cells sewn together. These simple cells will activate when external stimuli is orientated in a similar way

Question 12

What does orientation selectivity or turning refer to?

Answer 12

How the orientation of objects activates simple cells with an analagous configuration of photoneuron receptors.

Question 13

What is the PVC also know as?

Answer 13

V1. Here, information is then passed to range of other moduals.

Question 14

Overview of a hierarchical feed forward model.

Answer 14

This refers to the a hierachy of visual processing. Starting with V1 (orentation), and becoming more and more specific.

Question 15

What is the difference between dorsal and ventral stream.

Proposed by Milner and Goodale

Answer 15

Dorsal : Where objects are in particular location in the world.

Ventral : *What** object and visual identification .

Question 16

Which modual is most assoicated with colour processing?

Answer 16

V4.

Concious visual experience.

Question 17

Difference between parvocellular, and Koniocellular neurons?

Answer 17

Parvo: responsible for red - green

Konio: responsible for blue and - yellow

Question 18

Much like the inhibition / excitatory bullseye of a photoneuron, how does this work for colour?

Answer 18

There are oppoent cells. Meaning that red stimuli will inhibit green colour. Yellow stimuli will inhibit blue colour.

Question 19

What are the pairings of opponent ganglion cells.

Answer 19

Yellow - Blue

Red - Green

Question 20

What is the difference between damage to a colour cone in one eye, and damage to V4 in one hemisphere?

Answer 20

Missed a photoreceptor colour cone in one eye = colour deficency that exends accross the entire visual field

Damage to V4 in one hemisphere = half of our visual experience is colour

Question 21

What is Achromatopsia? Why is it unlikely?

Answer 21

This is partial loss of colour perception. This is unlikely because damage to V4 without damange to other moduals is unlikely.

Just colour.

Question 22

What modual is important for our experience of motion?

Answer 22

V5 / MT

Question 23

What is the difference in movement processing between LGN processing, V1, and V5/MT.

Answer 23

LGN (specifically mangocellular): registers patterns of light and movement but not with any specificity.

V1: responds to movement of bars or edged with specific orentation.

MT: Cell that respond to movement in a particular directio (left to right).

Question 24

What is the medial-superior-temporal (MST) responsible for?

Answer 24

• Optic flow (self motion = world motion)
• Complex motion
• Biological motion

As seen in monkeys

Question 25

What is Akinetopsia? How does it occur?

Answer 25

• Motion blindness.
• Bilateral damage to MT.

Example patient LM: see movement in frames.